1. Field of the Invention
The present invention relates to an apparatus for splicing, or connecting metal tube-covered optical fiber cables, and more particularly to such cables of long lengths and supplied on reels, and which provides for rapid and efficient handling of the spliced cables.
2. Background
Optical fiber cables range generally from several hundred meters to tens of kilometers in length; they are wound on reels or the like. In the case where a distance to be covered with a metal tube covered optical fiber cable is longer than the mentioned lengths of available optical fiber cables, two metal tube covered optical fiber cables must be connected together when the entire metal tube covered optical fiber cable is laid.
As a method of connecting such metal tube covered optical fiber cables, core optical fiber cables are exposed, that is, protruded from metal tube clad, or covered parts of the two metal tube covered optical fiber cables to be connected at their respective ends. A metal sleeve is pushed over the end of one cable and beyond the end to be spliced; the ends of the exposed optical fiber cables are then connected by fusion to each other; the metal sleeve, with an outer diameter close to that of the metal tubes covering the optical fiber cables covers only one optical fiber cable side, is then slid to a position over the splices. The metal tubes for the two optical fiber cables and the sleeve are connected, and sealed if necessary. Thereafter, the metal sleeve and the metal tubes are welded on both sides. In this way, the metal sleeve is connected to the metal tubes on both sides, and the two optical fiber cables are connected.
When both ends of the metal sleeve are welded to the metal tubes on both sides, their positions must be fixed and the metal sleeve and metal tubes must be respectively held. A welding head is rotated once peripherally to complete the weld.
Various methods of welding are generally known. However, since the metal tube is very small in diameter and thin in thickness, highly accurate welding is required and for this reason, laser beam welding is preferably utilized.
In the case of general welding other than laser welding, the metal tubes and metal sleeve are static without being rotatable, and a welding head, e.g., a welding torch makes one rotation around the periphery thereof. When the laser beam is used, accurate rotation of the head is difficult and an extremely complex mechanism is needed if the head is to be rotated accurately. Therefore, an apparatus has been employed by which the head is static, the metal tubes and the metal sleeve are accurately supported and the metal tubes and the metal sleeve are rotated at a constant speed.
After the weld is made, it is necessary to wind the optical fiber cable from a reel of the optical fiber cable through the splicing apparatus e.g., to another reel, in order to remove such connected optical fiber cable from the apparatus after the connection. This has greatly hampered work efficiency. In particular, this is a major problem when the optical fiber cable is long.